Web content, such as HTML or JavaScript for generating web pages, may contain application-like functionality that is interpreted and executed within a visitor's browser, or in a similar application. The general goal with HTML and other web technologies is to make them work, and work similarly, across many different platforms (e.g., Mac, PC, Linux, etc.).
To maximize the functionality of web content, it can be relevant for a system that serves the content to know the configurations of computers (whether desktop, smartphone, tablet, or other) that are being served the content. For example, particular knowledge can be obtained by identifying the type of browser that is rendering a web page, the operating system on which the browser is running, and plug ins that might also be operating on such computers. However, this additional supporting information must generally be sent from the various client computers to the server system, and such transmission adds overhead to the functioning of a browser presenting a web page or other application, which overhead is not directly responsible for improving operation of the page.